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Author:
waukeshaplumbing (WI)
having issues with a generator i piped to....ive done 10-15 before and never a problem..typically they are 5-10' from the meter...i either go under ground or strap to side of the house...3/4 is what i run.....
now i have a new one...ran good with its weekly test on/off for a few months...now is giving an error....Gas error....
house is sized to 1 1/2" pipe before the meter T since the house is 700,000 btu and at 70' 1 1/2 gives me 750,000....so my main is sized correctly...i ran 3/4 gastite approx 20' to the generator
im told the generator needed 1 1/4 to it by the electricians calculations
im told the generator needs a regulator (which i dont unerstand how it needs a regulator to go from normal pressure to normal pressure)
im told i need a 10' loop after the regulator
all of these things ive never done before, never had an issue
typically i would have ran this one underground since its 10' away instead of up and through the house....but the electrician told me of all their problems and talked me into it....basically i was told the piping was storage for startup...it needed the piping to use up a ton of gas at startup
i called the supply house and asked for a regulator....they have 2lb ones, but nothing that takes normal pressure to normal pressure....
ive been told i have too high of gas pressure (the regulator needed)
and im being told its undersized
trying to get a generac rep out there to tell me exactly what is needed....
anyone have any experience or advice?
the electrician makes it sound like 50% of their generators have gas problems......
my biggest curiosity....why does a unit that needs me to pipe 1 1/4 to it have a 1/2" inlet and come with a 1/2" flex pipe....how can 300,000 btu go through a 1/2" hole?
thanks for any advice
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Author:
hj (AZ)
One of your problems is you are listening to an electrician who has absolutely no idea what he is talking about. NOTHING he told you makes sense, but from here, I cannot tell you what the REAL problem is, expecially if you are coming directly from the meter to the generator for that short distance. IF you need a regulator, and you are working with a low pressure system, then it would be an "appliance regulator", like used on a gas range, and the company would usually send it with the generator.
Edited 1 times.
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Author:
m & m (MD)
What's the kW rating of the generator? What was your calculated btu rating? I think the unit is supplied with its own regulator like any other appliance (inlet pressure= outlet pressure).
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Author:
Paul48 (CT)
The size of the pipe has to do with the volume of available gas. Just like the burner on a gas boiler. The fitting at the burner will be smaller than the pipe required, and the orifice, smaller still. What are the btu requirements of the generator?
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Author:
waukeshaplumbing (WI)
300,000 btu i believe....
generac specs talk about a regulator...so im looking into exactly what pressure generac requires and im going to call Wisconsin Energies to see what pressure is coming out of the meter.....i could be having a too high of pressure issue or a lack of volume.....the error code is so stupid it doesnt tell you the difference...just a gas error code....its funny that this generator worked for months.....the electrician tested it after install..worked fine....now--bad
generac says to run a 10' loop of piping after the regulator (that they dont supply).....i just finished one for the same builder...this was a 2'lb system...so after the regulator i looped 8' of 3/4 piping in a circle around the unit(the instructions on this model said 6' was enough, but didnt give a pipe size)
it just looks stupid to loop the piping....ive seen generators before...never have i seen anyone loop it....but the electrician is telling the builder and im seeing it in the manual.....so i did it....we will see if this latest one starts up...i ran 1" 2lb gas across the house to it, so im not lacking btu's
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Author:
hj (AZ)
I have absolutely no idea what benefit a "loop" would give over a straight pipe the same length, and the regulaor is usually installed AT the appliance, NOT 10'-15' away.
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Author:
Paul48 (CT)
Three quarter inch is too small, by 50k/btus at that distance. It also suggests that the electrician could not have properly load tested the generator, as it simply would not achieve maximum rpm.
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Author:
bernabeu (SC)
? Does no one read the installation manual PRIOR to actual work ?
Or is it merely a matter of: It worked the last time I did it ! ?
.... rant over
==============================================
"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
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Author:
Wheelchair (IL)
Are you talking about a 10KW or a 17 KW? Some of those larger units burn 400,000 btu to start. 3/4 inch pipe won't work. Have you inquired with the local gas provider for an evaluation or "look see" What size?
Best Wishes
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Author:
m & m (MD)
3/4" gastite over 20' is way undersized for 300kbtu. CSST tube delivers approx. 35-45% less volume compared to steel pipe. Upsizing the tube may be all you need to do.
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Author:
Paul48 (CT)
I missed that csst was used. You're sized for slightly over 130k/btu. Our local gas supplier would send a plumber out to evaluate. What's wrong with this picture?
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Author:
hj (AZ)
INSTRUCTIONS? If we need the instrcuctions we will read them after the job is done. Besides what do engineers know about installing anything?
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Author:
hj (AZ)
OUR gas supplier would say, "It's after the meter so it is YOUR problem to solve it."
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Author:
waukeshaplumbing (WI)
here's the info from generac...talks of a step down regulator.....no idea what it is of it its even needed
i have researched it a bit more and agree 3/4 gastite was a mistake...im used to just burrying yellow underground 3/4 10' to a generator....i did not take into account the up/down of the gastite going up and over in a garage and then back down....now increasing it to 30' vs the normal 10'....plus i thought gastite had better flow than hard pipe since there were no 90's....
ive got tons of 1 1/4 underground gas piping...im going to just run 1 1/4 underground to the unit....it will be a 2 hour redo....i have 1 1/2 coming off the meter, so the house is sized correctly....i believe this is a larger than normal generator also...larger than ive worked with before....just doing the same thing youve always done w/o thinking and calculating is much of my error...
still have no idea what regulator is needed...unit doesnt come with one....and i have never installed a regulator before a generator...but they clearly say you need 10' of piping after the step down regulator....ive asked my supply house for a regulator and they dont stock one....only 2lb regulators..
A note of caution, only qualified electricians and contractors should attempt installation.
1. Step-Down Regulator is Not Installed in the Proper Location
When installing a gaseous generator at a new site, the generator is typically connected to local utility natural gas lines. Local fuel/gas codes dictate the maximum pressure under which natural gas can be delivered to a site or structure. The supply pressure from the utility meter/regulator is usually not the same as that required by the genset, so a separate primary or step-down regulator is needed to provide the correct pressure and volume of fuel to the genset.
From the primary or step-down regulator, gas flows through a flexible fuel line to the generator connection point, which is the unit mounted regulator.
What often occurs is that the step-down regulator is placed too close to the unit mount regulator. Typically, a minimum of 10 feet of pipeline is required. If the pipeline is too short, it may lead to hard starting, rough running, inability to carry load and erratic operation of the genset. (See diagram below.)
2. Pipe Diameter Size is Not Correct
When determining the appropriate pipe diameter size, the length of the piping as well as the number and type of fittings in the piping system must be taken into account. All pipe fittings (elbows, tees, couplings, unions, etc.) create a pressure loss. The more severe the elbow or turn (90 degrees versus 45 degrees), the greater the pressure loss due to the inherent resistance coefficient. Each pressure loss must be taken into account to ensure that the adequate diameter pipe is selected to maintain proper pressure to the generator. A system with several 90 degree elbows will likely require a larger diameter pipe versus a system with a straighter pathway to the generator.
3. Gas Supply Flow Does not Adequately Account for Overall System Demand
It’s vital that engineers and contractors understand the draws of the equipment being operated and the total amount of load on the system. The generator may be powering furnaces, dryers, refrigerated equipment, pumps, emergency lighting, etc. You need to understand the system, its configuration and various loads so that the piping is sized to provide adequate flow and pressure for initial loads as well as peak loads. Also, best practices for pipe and regulator sizing are to have a fuel flow delivery rating at least 10% greater than the 100% rated kW fuel consumption.
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Author:
Paul48 (CT)
What is the required supply pressure, according to the manual?
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Author:
bernabeu (SC)
Quote
....just doing the same thing youve always done w/o thinking and calculating is much of my error...
Been there, done that
==============================================
"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
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Author:
hj (AZ)
The "step down" regulator IS the pounds to inches one the supply house carries, but it is NOT relevant to your situation because you already have a low pressure system. It is probably caused by the undersized gas line, but your description also can be caused by moisture in the line if there is a low spot where it can accumulate and "shut off' the gas flow.
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Author:
waukeshaplumbing (WI)
im repiping it to 1 1/4 underground 10'
if 1 1/4 10' from a meter isnt enough gas for a 300,000 btu generator nothing will be...
i did notice in the photo's i got today it is a 3/4 feed....in the past they have all been 1/2" feeds, so this is the largest one ive done....
if i would have not listened to the electrician and just ran 3/4 underground 10' like i typically do i probably would have gotten away with it fine.....but now that its an issue i want to give it as much over kill as possible...i have 50'+ of 1 1/4 left over, so why not use it...
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Author:
hj (AZ)
quote; if i would have not listened to the electrician
If the blind lead the blind, will they not both fall in the ditch? What does an electrician know about a gas line?
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Author:
waukeshaplumbing (WI)
decided to do 2lb gas....2 regulators and im done....this way i dont have to rerun the generator line
easy/clean....multiple lessons learned...1- dont listen to anyone about what my job is....2- pay more attention to generators and the excessive btu....next time i have a house with a generator i will instantly go to a 2lb system and be done
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Author:
Paul48 (CT)
Around here, there are still neighborhoods that don't have 2 lb available. You need to have a plan, before you get to the job. I think that's why you got burned, listening to someone else. Before you get to the job, you need to have read the I&O manual. Most are available on-line, but if not, have the contractor provide it beforehand. It would be the same, if you were installing a boiler. You have to know the manufacturers requirements, or wind up in court because your way of piping the boiler doesn't work, or caused the boiler to fail.
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Author:
waukeshaplumbing (WI)
we figured out why the meter was undersized...the generator was added after the meter was there....i did this job almost a year ago, so i only 1/2 remember it and cant remember why i did what i did...but for the most part i just did what i always do....problem is its a much larger generator than ive done before...and i listened to electricians and ran it differently than before because of it.....you get used to doing something one way and you dont read instructions anymore....like putting a faucet in....after you do 5-10 of the same faucet you never look at a manual again.....ive done 10-15 generators, so i just put it in the same way as usual
funny thing today...this is same builder, but on a different generator (a smaller one)...the electrician told me the flex line it comes with must be straight...even a curve in the flex line (no matter how small) will effect how the generator runs...it restricts the flow...when our conversation was over i simply asked him----if 1/2 of the ones you install dont work and always need extra work why do you install generacs? if i had a water heater where i got 50% call backs i wouldnt keep installing them......his answer---generacs are 1/2 price compared to a Kohler
i had to adjust my piping to make his flex hose near straight for them to make him happy...
i made errors and it will cost me $400 in labor and parts to fix, but besides that what a POS of a generator....all i can say......poor homeowner has to look at 10' of 1 1/4 looping across his siding behind his generator....manual says it specifically...10' looped after the regulator..
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Author:
Paul48 (CT)
The electrician is "running scared". He doesn't understand gas line sizing. There is no way you should be so close with size, that a bend in the flex line would affect the way the unit runs. You figure your length in straight pipe, then add the equivalent length for fittings. If you are at all close when you look at the charts, you go to the next pipe size up.
I don't read that you have to loop 10' of piping at the unit. You need 10' of piping between the secondary regulator and the unit. If you have 1/2lb coming out of the meter, you need 10' minimum. If you're running 2 lb, don't put the regulator right at the unit, and then put an ugly loop. Move the regulator away. and provide a minimum of 10'.
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Author:
waukeshaplumbing (WI)
cant put the regulator anywhere but right behind the unit....the 3/4 line goes up from the basement, over the garage and back down and out....3/4 isnt big enough to handle the load, so i cant put it in the basement.....i dont want to bury a regulator in the garage attic.......nope...its going to look horrible.....it will be clean/straight and it will work....
i agree the electrician is insane or the generac generator is poorly designed to the point of insanity....
ive installed 10-15 generators in my career...100% have worked until this one.....done my way.....but this is not a normal generator...its much larger than any ive done
monday morning is the day.....got $200 in parts and 2 hours of labor....$500 out of my pocket to make it go away and make a homeowner happy....
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Author:
mrbill2413 (CA)
When installing a Generac Generator, or any generator, make sure you put in a drip leg and a sediment filter before the appliance regulator. It has to be put in. No water, no ice, and no gunk in the regulator. If you don't install them, you are guaranteed to have problems down the road.
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